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Date: Mon, 21 Aug 2017 23:20:22 -0700
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        linux-kernel@vger.kernel.org, Boqun Feng <boqun.feng@gmail.com>,
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        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Dave Watson <davejwatson@fb.com>
Subject: Re: [PATCH v2] membarrier: Document scheduler barrier requirements
Reply-To: paulmck@linux.vnet.ibm.com
References: <20170819043916.18725-1-mathieu.desnoyers@efficios.com>
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On Mon, Aug 21, 2017 at 10:42:36AM +0200, Peter Zijlstra wrote:
> On Fri, Aug 18, 2017 at 09:39:16PM -0700, Mathieu Desnoyers wrote:
> > @@ -3295,6 +3301,9 @@ static void __sched notrace __schedule(bool preempt)
> >  	 * Make sure that signal_pending_state()->signal_pending() below
> >  	 * can't be reordered with __set_current_state(TASK_INTERRUPTIBLE)
> >  	 * done by the caller to avoid the race with signal_wake_up().
> > +	 *
> > +	 * The membarrier system call requires a full memory barrier
> > +	 * after coming from user-space, before storing to rq->curr.
> >  	 */
> >  	smp_mb__before_spinlock();
> >  	rq_lock(rq, &rf);
> 
> Merge conflict here, current tip is over to smp_mb__after_spinlock().

Would some tree other than -rcu be better for that commit?

							Thanx, Paul